In recent years, touch device, due to having advantages of easy operation, has been widely used in many various electronic products such as a mobile phone, tablet computer, digital camera, music player, satellite navigation device and touch screen. Touch devices basically can be categorized into resistive touch devices, capacitive touch devices and optical touch devices, etc.; among which optical touch devices, due to having a better durability and a lower cost, have been getting more and more attentions.
FIG. 1 is a schematic top view of a conventional optical touch device. As shown, the optical touch device 100 includes a plurality of point light sources 110 disposed in the X-axis direction, a plurality of point light sources 120 disposed in the Y-axis direction, a plurality of light sensing components 130 disposed in the X-axis direction and corresponding to the point light sources 110 in a one-to-one manner and a plurality of light sensing components 140 disposed in the Y-axis direction and corresponding to the point light sources 120 in a one-to-one manner. A sensing area 102 is defined by the point light sources 110, 120 and the light sensing components 130, 140. The light sensing components 130 each are configured to sense beam 112 emitted from its corresponding point light source 110; and the light sensing components 140 each are configured to sense beam 122 emitted from its corresponding point light source 120.
When a user uses his/or her finger 50 to touch the sensing area 102 so as to perform a touch operation, some beams 112, 122 respectively emitted from the corresponding point light sources 110, 120 (for example, the point light sources 110a, 120a) are blocked by the finger 50 and accordingly some corresponding light sensing components 130, 140 (for example, the light sensing components 130a, 140a) may sense relatively weak optical signals; and thus, the optical touch device 100 can determine the position of the finger 50 according to these relatively weak optical signals. However, because requiring a relatively large number of light sensing components 130, 140, the conventional optical touch device 100 has a higher cost.